**1. Antibiotics and antibiotic resistance in the pre-antibiotic era**

Antibiotics are known to exist in the history of mankind since ancient times. They can be traced back to as early as 350–550 CE, when scientists found traces of tetracycline inhuman skeletal remains of ancient Sudanese Nuba [1]. This has led to the speculation that the diet of this population contained tetracycline. Even the red soils of Jordon which have been used since time immemorial to treat wounds have been shown to contain *Actinomycete* bacteria which produced actinomycin [2]. Antimicrobial activity is also present in many of the herbs used in traditional Indian Ayurvedic and Chinese medicines.

Antibiotics have saved countless lives, and at one point of time, we imagined that infectious diseases were conquered. Most of the advances of modern medicine including state of art surgeries and management of neutropenic, transplant and cancer patients are based on the use of effective broad-spectrum antibiotics. Thanks to the way we have handled these precious resources for treatment of variety of infectious diseases. However, we found to our dismay subsequently that we are stepping into the post-antibiotic era.

Antibiotic resistance genes have been present in nature long before the modern antibiotic era began. Some of the serine and metallo-beta-lactamases originated more than 2 million years ago [3]. It seems prudent to assume that the ancient bacteria had defence mechanisms (such as antibiotic altering enzymes or efflux pumps) to protect themselves from high antibiotic concentrations. Hence, the biosynthetic gene cluster that makes the "antibiotic" must also contain genes which confer "resistance" to these antibiotics, and many aspects of the resistome (collection of all AMR genes in a specific bacteria or ecological niche) might have developed much before these antibiotics became prevalent in clinical practice.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
